CN103618688A - Multi-carrier-phase modulation and relevant demodulation method - Google Patents

Abstract

The invention provides a novel signal modulation and demodulation method. According to the technical scheme, three coherent carriers are generated in a modulation process, a base band signal to be sent is deserialized into three base band signals, the three carriers are modulated respectively to obtain three modulation signals; and the three modulation signals are combined to obtain a multi-carrier-phase modulation signal. In a demodulation process, three local carrier signals are generated, and by mixing and matching filtering, three base band signals are obtained; and the three base band signals are subjected to coherent processing and parallel-to-serial conversion, and then originally-sent base band signals are obtained. The method has the advantages that the anti-interception capacity of the modulation signals is improved, the complexity is not increased, and engineering realization is easy.

Description

Multicarrier phase-modulation and decorrelation demodulation method

Technical field

The invention belongs to wireless communication technology field, relate to a kind of novel wireless communication signals modulation and corresponding demodulation method.

Background technology

Wireless communication signals modulator approach is by the baseband signal sending, to control the parameter of carrier wave, and the some of carrier wave or certain several parameter are changed according to the rule of signal, and the signal of generation is called modulation signal; Demodulation method is the inverse process of modulation, and its effect is the baseband signal of recovering original transmission from modulation signal.The effect of modulation-demodulation technique in communication system is most important, and the validity and reliability of communication system is had to very large impact and effect, directly affects the performance of communication system.

At present, the digital modulation signals adopting in wireless communication system generally can be divided into ASK(Amplitude Shift Keying, amplitude keying), FSK(Frequency Shift Keying, frequency keying), PSK(Phase Shift Keying, phase keying) and the QAM(Quadrature Amplitude Modulation of amplitude-phase associating keying, quadrature amplitude modulation) etc.The conventional method that digital modulation signals produces is to realize based on quadrature modulator, and the demodulation of digital modulation signals generally adopts coherent demodulator to realize.Realize best receptivity, require digital modulation signals design generally need meet vector space apart from maximum principle, be about to digital modulation signals and be mapped to by the two dimensional surface that carrier component and quadrature carrier components form in the same way, the vector distance between its signal phasor end points is maximum.Generally the distribution map of signal phasor end points is called to planisphere, be used for the performance of intuitive analysis digital modulation signals.

Digital modulation signals based on mentioned above principle design, as BPSK(2 system PSK), QPSK(4 system PSK), 8PSK(8 system PSK) and 16QAM(16 system QAM) etc., the limited and planisphere of its type distributes very regular.Therefore, the blind receipts of detecing in communication countermeasures field to conventional digital modulation signals are comparatively easy, in the situation that there is no any prior information of modulation signal, by signal interception, Modulation Types identification, communication signal parameters estimation and demodulation, adjudicate, just can carry out demodulation reception to the modulation signal of intercepting and capturing.Therefore, an urgent demand provides a kind of new anti-receipts technology of detecing, and makes conventional method cannot effectively carry out Modulation Types and identifies reconciliation transfer receipts, thereby improve the anti-ability of detecing receipts and secrecy transmission of wireless communication system.

Summary of the invention

For solving the anti-receipts ability of detecing of modulation signal itself, the invention provides a kind of new modulation signal design and demodulation method, the modulation signal that design realizes adopts existing method effectively to identify and reliable demodulation it, and the demodulation method of design can carry out reliable demodulation to designed modulation signal.

Technical scheme of the present invention is, multicarrier phase-modulation and decorrelation demodulation method, comprise modulated process and demodulating process, wherein:

First modulated process is to generate three-channel carrier (also becoming coherent carrier), wherein first via carrier wave and the second road carrier wave are mutually orthogonal, there is phase deviation and amplitude error in Third Road carrier wave and first via carrier wave, the setting of phase deviation and amplitude error value is received and transmitting ability integration the best anti-detecing, conventionally phase deviation value is (0, π/4] between, amplitude error value (0,1] between; By a roadbed band signal string to be sent and be converted to three roadbed band signals, and modulate respectively above-mentioned three-channel carrier and obtain three road modulation signals; After being closed to road, above-mentioned three road modulation signals obtain multicarrier phase modulated signal.

First demodulating process is the same homophase San road local carrier signal frequently of the carrier wave in generation and multicarrier phase modulated signal, Yong San road local carrier signal is carried out mixing and matched filtering with the multicarrier phase modulated signal receiving respectively, obtains three roadbed band signals; Utilize amplitude error and phase deviation construction solution correlation matrix between three-channel carrier, three roadbed band signals are carried out to decorrelation processing; The output signal obtaining after decorrelation is processed is adjudicated and parallel serial conversion just can obtain the baseband signal of original transmission.

The invention has the beneficial effects as follows: by constructing new modulated signal constellation, improved the anti-interception capability of modulation signal itself, make non-cooperative reception side in the situation that not knowing modulation signal relevant parameter, be difficult to Modulation Types effectively to be identified, also be difficult to realize reliable demodulation reception, thereby promoted anti-intercepting and capturing, the secure communication ability of whole communication system.Meanwhile, the new modulation signal for structure, the present invention proposes the demodulation that new demodulation process method can conveniently realize signal.When above-mentioned advantage is provided, the modulator-demodulator of the present invention's design is compared with general communication modulator-demodulator, and complexity increases little, and Project Realization is comparatively simple.In addition, simulation result shows by the parameter of modulation signal is rationally set, and can between the reliability of modulation signal and anti-intercepting and capturing, average out, and very large design flexibility is provided.

Accompanying drawing explanation

Fig. 1 is the multicarrier phase-modulator theory diagram that utilizes method design provided by the invention;

Fig. 2 is different parameters multi-carrier phase modulated signal planisphere;

Fig. 3 is the decorrelation demodulator theory diagram that utilizes method design provided by the invention;

Fig. 4, Fig. 5, Fig. 6 are different parameters multi-carrier phase modulated signal bit error rate performances.

Embodiment

Below in conjunction with accompanying drawing, the present invention is described in detail.

Fig. 1 is the multicarrier phase-modulator theory diagram that utilizes method design provided by the invention.Compare with conventional orthogonal modulator as seen, modulator of the present invention increases Liao Yi road carrier wave, between its phase place and homophase carrier phase, has deviation θ, and while amplitude is multiplied by gain A.Now, modulation signal can be expressed as:

S (t)=a ₁(n) cos (ω _ct)+a ₂(n) sin (ω _ct)+a ₃(n) Acos (ω _ct+ θ) (formula one)

A in formula one ₁(n), a ₂(n), a ₃(n) be Hou tri-road base band datas along separate routes, value be+1 ,-1}, the every symbol of modulation signal of generation transmits 3 bit informations, its efficiency of transmission is identical with 8PSK.

Fig. 2 is different parameters multi-carrier phase modulated signal planisphere.(a) in Fig. 2, (b), (c), (d) get under 10dB condition for signal to noise ratio, multicarrier phase-modulation parameter (A, θ) get respectively (0.5, π/16), (0.8, π/16), (0.35, π/16) modulated signal constellation and when (1, π/4).As seen from the figure, the planisphere that parameter arranges different multi-carrier phase modulated signal is more big changes, and even occurs the phenomenon that part constellation point overlaps.Now, the Modulation Signals Recognition algorithm based on conventional and quadrature demodulator cannot carry out correct identification and effectively demodulation to it.

Fig. 3 is the decorrelation demodulator theory diagram that utilizes method design provided by the invention, compares the output Y of the demodulator increase Liao Yi road carrier wave of the present invention's design and corresponding mixing, filtration module, particularly Dui San road mixing and filtering with conventional orthogonal demodulator _n=[y ₁(n) y ₂(n) y ₃(n)] ' understand relevant treatment, to realize the demodulation to multicarrier phase modulated signal.The decorrelation matrix of amplitude error between three-channel carrier and phase deviation structure that utilizes provided by the invention is as follows:

$R=\left[\begin{array}{ccc}1& \cos \left(\mathrm{\θ}\right)& 0\\ \cos \left(\mathrm{\θ}\right)& 1& \cos (\mathrm{\π}/2-\mathrm{\θ})\\ 0& \cos (\mathrm{\π}/2-\mathrm{\θ})& 1\end{array}\right]$ (formula two)

Because the matrix R order of directly constructing is 2, its inverse matrix does not exist, therefore need to be to matrix R and demodulating data Y _ndo necessary conversion process and obtain R ' and Y _n' carry out again decorrelation computing, its conversion is as follows:

$R^{\′}=R+\left[\begin{array}{ccc}1& 0& 0\\ 0& 0& 0\\ 0& 0& 0\end{array}\right]Y_n^{\′}=Y_n+\left[\begin{array}{c}\mathrm{sign}\left(y_1\left(n\right)\right)\\ 0\\ 0\end{array}\right]$ (formula three)

Last decorrelation is processed and is obtained being output as:

$\left[\begin{array}{c}{a}_1^{\′}\left(n\right)\\ a_2^{\′}\left(n\right)\\ a_3^{\′}\left(n\right)\end{array}\right]=R^{\′-1}\·Y_n^{\′}$ (formula four)

Above-mentioned output is adjudicated and parallel serial conversion just can obtain original transmission data.

In multicarrier phase modulating method provided by the invention, the modulated signal constellation difference that different parameters (A, θ) produces is larger, and its anti-receipts performance of detecing also has larger gap.Wherein, the value of θ (0, π/4] between, less its bit error performance of general value is better, but the anti-receipts ability of detecing is poorer; The value of A (0,1] between, the bit error performance of getting at 0.5 o'clock is best, but the anti-receipts ability of detecing is poor.

Fig. 4, Fig. 5, Fig. 6 are the multicarrier phase modulated signal decorrelation demodulation characteristic curve of error code that software emulation obtains, and the abscissa in figure is signal to noise ratio (unit is dB), and ordinate is the error rate.

What in Fig. 4, be labeled as " ☆ " is the characteristic curve of error code that conventional 8PSK modulation signal adopts quadrature demodulator demodulation to obtain.Wherein, that be labeled as " O ", " ", " △ ", "+" is respectively parameter (A, θ) get (0.5, π/16), (0.8, π/16), (0.35, π/16) and when (1, π/4), multicarrier phase modulated signal adopts the characteristic curve of error code of decorrelation demodulator.As seen from the figure, different parameters multicarrier modulated signal performance difference is larger, when constellation point vector distribution uniform (now the anti-receipts ability of detecing is weak), as the modulation signal of Fig. 4 (a), its bit error performance is even better than 8PSK signal, but when vector distance between constellation point is compared with hour (now the anti-receipts ability of detecing is stronger) demodulation bit error performance variation, even there is error floor.Visible, multicarrier phase modulated signal anti-detects receipts ability and error performance is conflict, has larger difficulty in practical application.

For improving the anti-error performance of detecing the multicarrier phase modulated signal that receipts ability is strong, the present invention has also introduced a kind of mechanism that repeats transmission, the data of carrier wave 1 are repeated to send, although now reduced the efficiency of transmission of system, can significantly improve the receptivity of decorrelation detector.

When the value of (A, θ) is (0.8, π/16) in Fig. 5, by employing, repeat the decorrelation demodulator demodulation characteristic curve of error code that transmit mechanism obtains.Be labeled as " ☆ ", "

", the curve of " △ ", " O " is when corresponding efficiency of transmission is every symbol 7/3,9/4,17/8 bit respectively, the characteristic curve of error code that adopts decorrelation demodulator to obtain.Visible, although now there is part constellation point to overlap, adopt conventional quadrature demodulator demodulation to receive, adopt decorrelation demodulator still can obtain good demodulation performance.

When Fig. 6 is (A, θ) value for (1, π/16), the Performance Ratio of multicarrier phase modulated signal and QPSK.The curve that is labeled as " ☆ " is the theoretical error rate of QPSK; When the corresponding efficiency of transmission of curve that is labeled as " O " is every symbol 33/16 bit, the characteristic curve of error code that the multicarrier phase modulated signal of employing obtains through decorrelation demodulator.Visible, multicarrier phase modulated signal not only error performance is better than QPSK signal, and the efficiency of transmission of its every symbol 33/16 bit is also better than every symbol 2 bits of QPSK.The above results shows multicarrier phase-modulation and the decorrelation demodulation method that the present invention proposes, and except providing preferably anti-detecing to receive performance, rationally signalization parameter can also obtain than the better transmission performance of conventional modulation signal.

Above-described embodiment of the present invention, does not form limiting the scope of the present invention, any modification of doing within the present invention spirit and principle, is equal to replacement and improvement etc., within all should being included in claim protection range of the present invention.

Claims (2)

1. multicarrier phase-modulation and a decorrelation demodulation method, comprise modulated process and demodulating process, it is characterized in that:

First modulated process generates three-channel carrier, and wherein first via carrier wave and the second road carrier wave are mutually orthogonal, and Third Road carrier wave and first via carrier wave exist phase deviation and amplitude error, phase deviation value is (0, π/4] between, amplitude error value (0,1] between; By a roadbed band signal string to be sent and be converted to three roadbed band signals, and modulate respectively above-mentioned three-channel carrier and obtain three road modulation signals; After being closed to road, above-mentioned three road modulation signals obtain multicarrier phase modulated signal;

First demodulating process is the same homophase San road local carrier signal frequently of the carrier wave in generation and multicarrier phase modulated signal, Yong San road local carrier signal is carried out mixing and matched filtering with the multicarrier phase modulated signal receiving respectively, obtains three roadbed band signals; Utilize phase deviation and amplitude error construction solution correlation matrix between three-channel carrier, three roadbed band signals are carried out to decorrelation processing; The output signal obtaining after decorrelation is processed is adjudicated and parallel serial conversion obtains the baseband signal of original transmission.

2. multicarrier phase-modulation according to claim 1 and decorrelation demodulation method, is characterized in that, utilizes the decorrelation matrix of amplitude error between three-channel carrier and phase deviation structure as follows:

$R=\left[\begin{array}{ccc}1& \cos \left(\mathrm{\θ}\right)& 0\\ \cos \left(\mathrm{\θ}\right)& 1& \cos (\mathrm{\π}/2-\mathrm{\θ})\\ 0& \cos (\mathrm{\π}/2-\mathrm{\θ})& 1\end{array}\right]$

Wherein three-channel carrier of the present invention utilizes quadrature modulator principle when generating, and except utilizing the two-way carrier wave of quadrature modulator, then increases by a road carrier wave, and the deviation existing between this carrier phase and quadrature modulator homophase carrier phase is θ.

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